The present invention relates to an apparatus for printing solder balls on an electrode on a surface of a substrate.
Japanese Patent Application Laid-Open No. 2004-62505 discloses a conventional method of printing solder balls in which solder balls are fed onto a mask (alignment member), and then a sieve having two or more wire rod members which are arranged in a state where their rod centers are nearly aligned is allowed to move in the horizontal direction while pressing the wire rod members by using the sieve in a state where the wire rod members can abut on the solder balls with substantially-horizontal postures, so that the solder balls are fed to an opening portion of a mask surface.
As similar to the above, Japanese Patent Application Laid-Open No. 2005-343593 discloses that by using a sieve including a plurality of wire rod members, the wire rod members are arranged while being closer to the sieve in the vertical and horizontal directions with respect to the moving direction of the sieve.
In the method of using the sieve, a feeding port for feeding the solder balls onto the mask and the sieve having a plurality of wire rod members to squeeze the solder balls into the opening portion of the mask surface are provided, and the wire rod members are arranged so as to abut on the solder balls with horizontal postures. In addition, a ball feeding portion is provided at a right end of the mask, and a sucking port for sucking the solder balls is provided at a left end. That is, the ball feeding portion is configured separately from the sieve. Therefore, a fixed amount of solder balls which is larger than the number of electrodes is weighed to be fed onto the mask surface from the ball feeding portion, and the solder balls are fed to the opening portion of the mask by horizontally moving the sieve. Accordingly, in the case where the opening portions of the mask are continuously provided in the moving direction of the sieve, the opening portions into which the solder balls are not fed are possibly present. In addition, there possibly occurs a case in which a large amount of solder balls are fed to the opening portions, and it is difficult to adjust a feeding amount of solder balls. Further, the above-described documents do not disclose how the wire rod members which are provided at the sieve for the solder balls and whose rod centers are nearly aligned are vertically and horizontally closer to the solder balls. In addition, the wire rod members are allowed to abut on the solder balls with horizontal postures, and there is a possibility of generating defects known as double balls which are caused by squeezing extra solder balls into an opening portion of a mask.